Testing system



.I une17, 1930. w. BREsTERs 1,763,878

TESTING'v SYSTEM Filed oct. 26,1928 4 sheets-sheet 1 R T 5y W BREST/ERSY Ff ,5 HG1 H52 Ha/:f5.4 WMV June 17, 1930. w, BREsTERs l 1,763,878

TESTING SYSTEM Filed oct. 26, 192s 4 sheets-sheet 2 /N W RESTERS June17, 1930. w. BRESTERS 1,763,878

TETING SYSTEM V A Fillahoct. 2e, 192e 4 sheets-sheet 3 Fla". 3

/N VEA/TUR W BRESTERS June 17, 1930.

W. BRESTERS TEsTING SYSTEM l Filed OCT.. 26, 1928 TENS 5 Fla. 4

fwn/mf? W BREST/ms 5y 4 Sheets-Sheet f1- Patented June 17, 1930 cuirserstes; .tra-'r winnen Bitiisiiiis'gfo ianitivngwiiziiiiois, Assieitoiteen Pans recensement; op New Yoan, 1v; Y' citr'caarioit er new' YonexTESTING SYSTEM- Appuctidn inea octebe'r' 2e, 1192s.; serai No; 315,115.

This invention ,relatesl toV telephone systems and particularly totesting means for automatic telephonel systems. Y y

nobject of this invention is to improve and simplify the testing ofautomatic systemsv previously used by means of a test-A switches. U y

Heretofore systems have been usedl for testing. for short-'circuitechopened, and reversed wires and forother troubles that are likely tooccur in connections for' automatic switches. y ,Y .y

i ccording to the present invention an advantage has been secured over'the testing ing device arranged so that one series of switches alreadytested may be disconnected -from the deviceand another series connectedthereto for testing while a third series is be- 4 ingl tested. f

Another1 feature is a testing device for test- Y ing" two-motionswitches which is so ari ranged that the wipers of such switches aredirected to travel over the terminals of suc- .ceeding groups byreleasing the switchin regard toits secondary directive movements onlywhile transferring from one group to' another. y .0 y y Another featureis t-he provision of means in the testing devices whereby theconnections between two or three switches may be tested' automatically.lf two switches are lconnected for testing, the testing devicesimplyproceeds with the test andindicates whenit is completed, whereasif three switches are connected for test, the-testing device proceedswith the testing of the connection between the lirst and they secondswitch and when this test" is completed it proceeds; automatically totest the'connection between the second and the third switch. 4 L

The invention vhas been illustrated in the accompanying drawings Y, inwhich Fig. 1 shows in diagrammatic form portions of a plurality ofautomatic switches and the manner in which they may be connected" fortesting,l while Figs. 2, 3 and 4 show a testing device embodying thefeatures ofthis inven: tion. Fig. 2 shows primarily' keys foi-trans# 1ferring the testing device from one'series of switches connected fortesting to another connected series of switches, and signaling lamps toindicate test conditions. Fig. 3

shows Vmiscellaneous control relays, keys and lamps; employed. in thisfdevice, while;n show-s step by stepY selector switches for vcontrollingthe progressy of the tests, and signals for visually1 indicating thisprogress. Figs. l to 4 should be arranged asv illustrated infFig.-5. i

vReferring now to the drawings, the testing'device is so arranged thatgrou-ps of.

switches, such as line finders for eXamplefof adideren-t number ofswitches ineach groupl` mayv be tested.-` In Fig.l 1` has been shownthe` firstY row o r level of termina-ls of each of'` 6 switehes ofagroup of 30. Switches-1,2, 1l, 12,. 21 and A22have been indicatedforre'asons which will be;` hereinafter described; The

testing deyice has also been'arranged for; the testin'gof two other'groups`A o'f 2d and: 126 switchesrespectively. Y

To test` group' of 3G-A switches the: connec-v` tionsv from'Y thetestingl device are: changed eight successi-ve' times and the' testingof the switches 'arranged as follows: .z

First testbetwen 'switches 15,11 and" 21 Second test/between switches2', `12 and 22' Third test .betweenf'swfitchesf 3, 13 and 23" Fourthtest between switches 4;- 14" andjt Fifth test Vbetween switches 5; 15Land lSi-Xth test between" switches'VT 6; f6' and 26 Seventh testbetweenswitches"7,1l lf? and' 2"-7 Eighth test-.betvveen1 switchesY 8,1'8 and" 28' Niiitlr testi between' switches 9', 1'9" and'v 29rlfenth'test` between switches l0; 20 and 30 To test" a group" of l2Oswitches the coiinee-l' tions' froin. the testing devices lare alsochangedZ .eight successivetimes and the test'- eli Y ing oftheswitchesin in this manner the number of changes that have to be Vmadearereduced to a minimum. For example, 1n the '1, case of the 30 switch testthe switches 1, 11

and 21 are connected to the normal contacts of the-transfer keys 200 inFig. 2 while the switches l2, 12 and 22'are connected to the alternatecontacts of these'keys. In this manner the first threeswitchcs'mentioned will be tested with the transfery keys in normal andthe second three 'switches mentioned will be tested with the transferkeys operated. When the transfer keys have been operated and while thesecond groupv of switches are being Ytested the first group of switchesmay be ldisconnected from the keys and switches`3, 13 and 23 connectedin their places, and when the transfer keys are returned to normal andwhile this third group kof switches is being tested, the second group ofswitches may bev disconnected and switches 4, 14 and 24 conne'cted intheir places.- Proceeding in this' manner only eight successivechangesneed to bernade during the testing of the groups of 30 and 20switches each, while only six successive changes need to be Vmade duringthe testing of the group containing 16k switches.

' The connections required lfor each switch to prepare it for testingare as follows l Connections from the transfer keys to the siX wipers T,R, T1, R1, S and S1. These connections are made for testing opened,shortcircuited and reversed wires among the Amul-` tiple lconnectionsbetweenthe .switches under test, connectionsto .thev frames of theswitches to be tested for short-circuits and connections 'to thewindings of the lvert-ical, rotary and release magnets to put them undercontrol of the testing device. In i connecting a switch for i testingthe normal battery connections for the switches are removed.` Batteryconnections for the lines to which the switches have ac# cess are alsodisconnected in order that thev switches during their testing operationmay not disturb the conditions on these lines.

A description will now be made ofthe procedure in. testing a group of 30switches. The testing may .begin automatically with switches, 1, 2,11,12, 21 and 22 connected as shown in Fig. 1 and with the transfer keys200 and control keys 201 and 206 in normal positions and the start key300 and the power ykey 301 operated and with key 325 operated to closeits uppercontacts. The rst effect lt-will'be noted thatby arranging thetest-V will be the closing of a circuit for the opera- 11 and 21. Thecircuit for relay 303 may be traced from battery through the left ,handVwinding of this relay, brush of bank 403, position 3 of the selector 401and brush of bank 405, position 2.of-theselector 406 to ground. Thecircuit for vertical magnet 101 may be traced v from battery through thekey` 301, armature and front contact of relay 303, vertical magnet101,lead 34, transfer key 200,

brush of bank 407, brush of rbank 402 to i ground. The circuit forvertical magnet 102 may be traced from the same battery through lead 43and the transfer key 200 to the ground at brush of bank'402, while thecircuit for vertical magnet 103,1nay be traced from the same batterythrough lead 52 and keys 200 and 201 to the same ground. Relay 304alsooperates from the ground at the brush of bank 405 over an obviouscircuit. This relay, how

ever, is slower in its operation than relay 303 so it will not operateuntilthe vertical magnets have been operated to advance the brushes Vofthe switches to the first level.V

l/Vhen relay 304 does operate theY stepping magnet 408 for selector 406is operated over a circuit as follows: from battery through the windingand the self-interrupting conl tact of magnet'408, right hand armatureand front contact of relay 304,brush of bank 405 to ground. Magnet 408in operating moves the brushes of selector 406 to position 3. In in thislposition the circuits for the vertical magnetsk are opened and circuitsfor the rotary magnets uof switches 1 and 11 closed as well asl thecircuit for the battery supply relay. 307 for these rotary magnets. Thecircuit for relay 307 may be traced from battery, left hand winding ofthis relay, brush of bank 409, position 3, brush of bank 410, position 2of selector 411, key 305, inner left hand armature and back contact ofrelay 306 to ground. Relay 307 in operating closes the circuit frombattery for the rotary magnets 104 and 105. The circuit for magnet 104is as follows: from battery throughcontacts of key 301, armature andfront contact of relay 307, rotary magnet 104, lead 35, transfer key200, brush of bank 412 of selector 411, brush of bank 413, key 305,inner left hand armaturev and back contact ofV relay 306 to ground. Thecircuit for the rotary magnet 105 maybe traced from-the saine battery'through lead 44 and the same ground at relay 306. 1 The operation ofthese two rotary magnets'will advance the brushes of switches 1 and 11to the rst sets of termina-ls in' theV irstlevels'of thesevtwo switches.The slow to operate relay 308 is also operated by the same ground atrelay 306 from battery through its winding. Relay 308 does not operateuntil the rotary magnets have operated. When' the' selector 406 shiftedto position 3, relays 303 and 304 were released; relay 303 to open thebattery connection for the vertical magnets and relay 304 to open thecircuit for' magnet 408 of selector 406. Relay 308 in operating closes acircuit for the operation of magnet 414 of selector 411 to switch itsbrushes to position 3. rEhe circuit lor this magnet may be traced' frombattery through the Winding and the self-interrupting contact of magnet414, 4armature and front contact of relay 308, brush of bank 410,position 2, key 305, inner left hand armature and backV contact of relay306 to ground. When selector 411 switches to position 3v the brush ofbank 410 opens the circuits for relays 307 and 308 and the circuits forthe rotary magnets. rlhe selectors 401., 406 and 411 are now in theirpositions 3 and switches 1 and 11 are readyy to be tested in regard tothe multiple connections between the terminals ot the first lines.

It no irregularities are encountered inthe connections between these twoswitches, lamps T,R,T1,R1,S and S1 are lighted. The operations leadingtov the lighting of these lamps are as follows. It the connection between the tip terminals of switches 1 an'd 11 is completed over themultiple leads, a circuit will be established through relays 202 and 203as follows battery, winding of relay 202, lower, outer armature and backcontact of relay 204, key 200, lead 28,. tipfbrush of switch 1 multipleconnection from the tip terminal of the irst set of terminalsof'thisswitch to the corresponding tip terminal of switch 11, tip brushof this switch,y lead- 37,

hand armature and back contact of relay 310,

left hand armature and back contact of relay v 311 to ground. Due to theresistance 205 in this circuit the marginal relay 202 will not operate,but relay 203 operates to close a' circuit for lamp T as follows:battery, lamp" T, upper outer armature and `trent contact f of relay203, to ground at the armaturey and back contact of relay 102, It theconnection is completed between the ring terminals of switches 1 and 11,a circuitwill be completed for relay 207 'from battery, winding of relay207, key 200, lead 38, ring brush of switch 11 and ring terminals of thefirst line through the multiple connection to the Vcorresponding ringterminal of switch 1, ring brush of this switch, lead 29, 'key 200,upper inner armature and back contact of relay 204, conductor 208,l tothe ground at-the lett hand armature andi back contact of `relay 3111',ashereinbetore described. The-operation of relay 207 closes a circuitfor the lighting of lamp R, from battery through lamp R, upper outerarmature and fronty contact of relay 207, armature and back Contactofrelay 202, toground. It' the connection for the T1 brushes iscompleted through the switches 1 and 11, a circuit will be completedv:tor the operation of relay 209 as follows: battery, winding or relay210, third lower armature and back Contact of relay 211, key 200, lead301,1l brushes and terminals and the multiple connectionbetweeniswitches 1 and 11,lead 39, key'200, resistance 212, winding ofrelay 209 to the ground heretofore traced for the operationot relay 203over lead 208. Relay 209 in operating completes the circuit for thelighting of lamp T1 from battery through this lamp, upper outer armatureand front contact of relay 209 to groundA at the armature and backcontact of' relay 210. lit the multiple connection between the brushesR1. oiz switches 1 and'llis intact, relay 213 will operate over acircuit from battery through' the winding of this relay,A key 200,lead-'40, R1k brushes andV terminals of switches 1 and 11 and themultiple connection therebetween to lead 31, key 200, secondi upperarmature and back contact of relay 211, to the ground over lead 208.Relay 213-in operating closes the circuit for the lighting'L of lamp R1from battery through this lamp, upper outer armature and iront contactofV relay 213, toground at the front armature and? backv contact otrelay 210. Similarly it the circuitsw for the S and S11 brushes ofswitches1 and.11 are completed through the multiple connections, relays214 and 215- will be operated through obvious circuits over leads 32 and41 and'42 andi-33. The lamps S' and S1 are thereby lighted throughcircuits completed by the operation oirelays 214 and 215 to ground.

When-relays 203 and 207 have operated a circuit is completed for theoperation of relay 204 as follows: battery, key 201, lower winding ofrelay 204, third outer armature* and front contact of relay 207, outerupper armature and front Contact of relay 203 to groundl at the armatureand backcontact of relay 202. Similarly the operations ot re-V lays 209and 213 will close a circuit for the operation of relay 211; In: thiscase the circuit may be traced from' the battery at`r key 201 throughthe lower winding of relay 211i, other contacts of key 201, armaturesand' front-contacts ofrelays 2-13 and 209toy ground at relay 210. Relays214 andl 215 also close an obvious circuit lfor relay 216 through itslower winding and contacts of key 201. rlhese three relays in operating!provide locking circuits for themselvesto the groundover lead 208, openthecircuitsfor relays 203, 207, 209, 213, 214 and 215 and leo Vthetrouble key 206.

also remove the battery from the reverse lampsTR, TlR1 and SSl toprevent false operation of these lamps at this time. A circuit :torrelay 312 is also -prepared from batterythrough the winding of thisrelay, lower outer armatures and front contacts of relays 216 and 211and third upper armature and front contact of relay 204 to ground atRelay 312 in operating closes a connection from the battery supply forthe operation of the rotary magnet 106. This circuit may be traced frombattery, key 301, outer right hand armature and front contacto'l relay312, winding of `magnet 106, lead 53, key 200, middle right handarmature and front contact of relay 312. This magnet net 106vnowoperates to advancethe brushes of switch 21 to contact with theterminals kci? the iirs-t row for the testing of the multi! pleconnections of the first set of terminals oi these switches may betraced as follows: for'the tip connection, battery, wind- Aing of relay202, lower outer armature and `front Contact of relay 204, key 200, lead46, tip brush of switch 21, multiple con- Y nection lto switch 11, tipbrush of switch 11,',V lead `37, key 200, resistance 205, winding vottrelay 203 to ground over lead 208. For the ring connection, battery,winding of relay 207, vkey 200, lead 38 over the ring connection, lead47, key 200 to ground at trouble key 206; The T1 con-k nection lor relay209 will extend from battery, Ythrough winding of relay 210, third lowerarmature and front contact of relay 211, key 200, lead 48, T1connection, lead 39, resistance 212, winding of relay 209 to groundoverlead 208. Y The R1 connection for relay 213 will extend .throughleads 40 and`49l second upper armature and front contact of re# lay 211to ground on lead 208.v The S connection `for relay 214 will extend frombattery, winding oi relay 217, third lower armature and` yfront contactlof relay 216, lead 50, S connection, lead 41, resistance 218, windingof relay 214 to ground on lead 208, while the S1 connection vfor relay215 will extend from battery through winding of relay 215,'

lead 42, S1 connection lead 51', the second upper armature and frontcontact of relay 216 to ground on leadv208.

and 215 will operate to light lampsS andrSl. The lighting of these lampsthe second Vtime indicates that conditions on the multiple connectionsbetween vswitches y11 standard.

After theserelays have operated and due to the operation of relay 313, acircuit is now completed for the operation of relay 314 as followszbattery, windingof relay 314, middle left hand armature and frontcontact of relay 313, second lower armature and front contact of relay216, second upper armature `and 21 are and front contact of relay 215,inner upperV armatures and front contacts of relays 214 and 209, secondupper armatureand front contact ofrelay 213, second lower armature andfront contact of relay 211,' inner `lower armature and front Contact ofrelay 204, second upper armature and front contact ofre-` lay 207, upperinner armature andA front conltact-o1c relayY 203 to ground. Relay'314inl operating closes an obvious circuit for4 the operation of relay V309and also provides an energizing circuit for relay 307 which in operatingsupplies battery'for the operating magnets ofswitches 1, 11 and 21 ashereinafter to be described.V Relay 309 in operat-A ing provides alocking circuit for itselfV through its inner right hand armature andfront contact to ground on the brush of bank 402. Vhile relay 309 opensthe circuit to ground a relay 311 for lead 208 thus causes the releaseof relays 203, 207,209, 213, 214

and 215 and these relays in releasing ex-V tinguish the lamps. undercontrol of these relays. These relays in releasing open the vcircuit forrelay 314 which is now also reo advanced to positionk 4, but thisshifting'oi Y the brushes of switch 401 does not take place until therotaryv magnets 104 and v105, of switchesl and 11, areA operated as thecontacts of relay 314 are arranged to close the connection through `itsright hand armature and back contact before -it closes the connec- -tionthrough its outer left hand armature and back contact. These rotarymagnets are operated over the following circuit; battery,

through contacts of key 301, armature and front contact of relay 307,and in parallelthrough windings of magnets 104 andA 105,

and leads 35 and 44, through key 200, brush of y bank 416, position 3,back contact of relay 314, front contact of relay 309, brush of bankV13o C mesme 415, position 3, back contacts of relayslO and 311 toground.

The testing ofthe connections between the rst set of terminals ofswitches 1, 11v and'21 is now completed; the selector l401 has beenadvanced topposition 4 andthe lbrushes of switches and 11 have beenadyanced `to connect lwith ne second set of terminals .to test theconnection between these two switches at this point. fis switch 401 isadvanced to the 4th position, relay 309 is regl-eased. The .testing ornthe second the remaining sets lof terminals in the tir-st level ofswitches l, 11 and 21 is done in the ine as @herein before described forthe irst--setot terminals of these three switcles. Further descriptionalong these lines is therefore considered un.- necessary, eXcept'to saythat the selector 401 is actuated to shift its brushes one step forreachset of contacts tested in this leyel.

It should, however, beobserved .that .on the first step of .the brush.of bank 417 .ort .selector 401,11 .connection is established for .thelamp #l of .the set ,.o .ten unit lamps 418 and Ythat on each succeedingstep the corresponding lamp inthis series is `lighted to indicate the.sets .of terminals tested. Similarly, thetirst operation .of switch40.6 will cause a connec- ,tion .to be made from ground through ,thebrush of :bank 4.05 for `the lamp #l of .the set often tens lamps 419 toindicate that .testing vis taking place Vin vthe y:first level .of theswitches.

The lamps 1-.-2 and x2f--3 will indicate whether testing is taking.place between switches 1 and 11 or between lswitches 1.1 and 21. It willbe .noted .that lamps 1-.2 will .operate long as relays 2.04, 211 andi216 are not operated. lt' these relays `are ,operated lamps 2-.3 willoperate to indicate vthat test-- ing is takingplace between .switcheslland 21A.

It unstandard conditions exist in the lmultiple connections between theterminals of tr e tested switches or if any one ot t-hetrames .of theseswitches is grounded, the .test circuits will stop-functioning and theselectors will remain inthe position where the trouble is encountered. fl i For example, if there `is a ground connection on the frame of anyone ol :the tested selectors relay 310 willoperate from battery through,the fr-ame ground hey 32.7, .winding of relay 3,10, ground on lead 3.6,if the trame of switch 1 is ground .or -onyleadf`45 it the trame ot theswitch 11 is ground loron lead 54 if the trame of switch 21 is ground.lie-V lay 310 in operating opens atth'e outer right hand varmature andback contact the vcircuit from ground at the lefthan-d'armature and backcontact of relay 311 'for the operating circuits of the rotary magnets,

If any or" the multiple leads between the testing switches ,are open,the tip ,and ,ring multiple connections,v for example, thenthecorresponding 'lamps'T or R are not lighted.

In such a case the Arelay 314 will notoperate and hence cause the switchto stop on the terminalsot the defective connections.

It anyvof the multiple connect-ions lare reversed, the correspondingreverse lamp will be lighted. For .exam-ple, in case, the reverse lamplightshe conditions wo be such that the ground connection that isnormally on the ring brush of switch 1 through lead 29 will be suppliedthrough. the tip -brushot` switch 11 and lead 37 thus preventing theoperation of relay 203 through the resistance 205. TW hen this takesplace Athe reverse lamp TR will lightfgrom battery at the fourth upperarmature and back contact ot relay 204, which naturally will notbeoperated at this time, through. the reverse lamp TR, upper innerarmature and bvaclrcont-act of relay 207, lower armature .and backcontactot relay 203, key 200, lead 37, reverse connection, llead 29, key200, upper inner armature and back contact of relay 204, vto ground .onlead 208. Relay 207 will ofcourse not operate under these circumstancesas the normal ground @Ver lead f2.9 will not be supplied -to'lead 38 andthe ring brush of switch 11, and as the tip brush of switch 1 isconnected through the ring brush of switch 11 and" lead 28 through relay202 to battery no operating circuit for this la-tter relay will 'becompleted.

Similarly, the reverse lamp T1R1 or reverse lamp SSl will light'it thecorresponding ref. lays fail to operate due to reverses onr any of theother multiple connections between switches y1 and 11 or for that matterybetween switches 11 and 21, depending on the switches testedat thetime. Y l 7 it any of the .multiple connections are short-circuited,relays 202, 210 orV 217 will operate to light the corresponding lamp TR,'llltl or. S551; For example, if ashort-circuit exists between the tipand ring conductors, relay A202 will operate. 'Relay 202 will operatefrom ground through lead 28, .tip brush of switch 1, and through theshort-circuit to ring brush of switch 1- and lead 29 vto ground. ln thiscase lamp TR will light to indicate a short-circuit between these .twoconductors. Due to .the .opera-tion' of this relay andA thenon-operation ci' relay 203, relay 314 will not operate and theswitchwill stop `on the terminals on which the trouble occurs. Relay 203will in this case be shunted by theground en "lead- 29 ironiathev ringbrush of switch 1 through the short-circuit to the tip brush of switch1l' and lead While rrelay 207 will opcrate through the short-circuitthus preventthe reverse lamp TR from'lighting at this time. Y Similarlythe lamps TlRl' and S51 would light if the short-circuit existed betweenthe Tl and multiple connection and the Sand Si multiple connection. K w

lf any 'of the above unstandardl conditions egrist and it is decided tocontinue to the test, the frame ground key 327 will'be operated in case.ground exists in any of the frames torelease-relay 310'to permit thetestto continue. If any of the othertroubles occur the trouble key' 206will be operatedV to remove the ground connection for relays 203, 209and 2 14' or 312 and to place ground on a vcircuit for relay 314, Relay314V in y operating causes the.' test to be continued -as hereinbeforedescribed. A Y y If noV unstandard conditions exit, the tests mayproceed from one set of terminals to another in the first level ofswitches 1, 11 and 21 in the manner described above.` When the tenth setof contacts is reachedand tested selector '401 will have its brushesAlocated in position 12.` In this Vposition the brush of bank 417 willsupply ground for the operation of relay 317 which in turn causes theop- A erationof relay 303. This relay provides'batmagnets.

tery connections for the vertical and rotary tical magnets of switches1, 11 and 21 is pro-Y vided as follows: fromthe battery supply'at key301 throughthe vertical magnets 'over conductors 34,43 and 52fkey 200,`through `thewinding of vrelay 319, key 325, brushof bank'422, position3 of selector ,411, brush of jso bank 416 of selectory 401,positon12','outer right hand armature andback Contact of reiay 314,lefthandarmature and front Contacty of relay 309, brush of bank 415,position 12,

. outer right hand armature and back'contact Vand causes the operationof relay 302 over an;

vof relay 310, left hand armature and back cont-act of relay 311 toground. Itr should be remembered that relay 309 is operated at thistime, beingQheld by vground'on brush of bank 403, position 12, 'saidground being supplied fromV the right hand armature and front Contact ofrelay A317'. Relay 314 isreleased at `this time. g y

-It should benotedthat the circuit traced for the verticalomagnetspasses through the winding of relay 319. The vertical magnets will beonly partially operated at this time dueto the resistance of the windingof relay 319, soas to prevent the switches from releasing inthe verticaldirection. That is, the pawls ofthe vertical magnetswill engage thesecondV tooth on the shaft of the switch but willnot cause the shafttobe lifted to bring thefbr'ushes to the second level at this time. Relay`319, however, operates inthe circuit circuit maybe traced from batterythrough the armature and front contact of relay 302 and second righthand armatureand front contactV of relay 319, .windingof relay A322,

and'lead60, which ismultipled to Yall three vrelease magnets 108,` 109,110 'of the switches 1,;111and721, .through the windings of theirrelease magnets 'and' ajmultiple connection to ground., Thus, switches1,11 and 21 will At this time ya circuit for the ver- Y magnets asfollows: relay 322 operates inthe release circuit and closes acircuitforthe operation of relay 323 as follows: battery,

winding of relay 323, armature and front contact of relay 322, brush ofbank 410', position 3 of selector 411, contacts of key 305, innerlefthand armatureA and back contact of relay 306. Relay 323 provides alocking cir'- cuit for itself through its Yinner left hand so narma-ture and front contact to ground at ythe brush of bank 402,position 12 of selector- 401. Relay`323 in operating closes an obviouscircuit for the operation of relay 31.6v from ground at relay 311. Relay316 in op# erating closes a shunt Varound relay 319l so that thevertical magnets of all three switches are now.operated fully and thusadvance the brushes of these switches vto the second level of terminals.y

Relay 319 is released by this shunt circuit causing relay 302v torelease. VThis rrelay vis f i slow in releasing to permit the verticalmagf nets to operate before selector 401 is actuated'.

to shift its brushes to position 13. Relay 319 in'releasing closes acircuit for the operation of relay 311 as follows: battery, winding ofthis relay, outer right hand armature Vand,

back contact of relay 319,"middle left hand armature and front contacty,of relay 323 tov ground at the brushof bank 402. Relay 311 V inoperating opens the connection to ground for lead 208 and closes aconnection to ground for the operation of rotary magnets 104 andA beforerelay 302 is released tooperate mag` y net 400 to shiftthe brushes ofselector 401 from position. 12 toposition When 'relayv 302 does releasea circuit for the operation Vof Y magnet 400 is Vcompleted as follows:battery,

armature andback contact of relayf'302, 'winding and selfinterruptingcontacts of magnet p 400, outer left hand armature and back contact ofrelay 314, outer right hand armature and front .contact`r of relay 309,innerright hand .armature and front contact?of'relay 309, brush of .bank'403, right hand armature and vfront ,contact of relay 317 to ground'.When theselector 401 moves to position 13 the locking circuit forvrelays 309 and 323 are opened aswell asthe energized circuit `formagnetl400. f These relays release and Vrelay 323v causes thev releaseof relay 311.VV Relay 311 thuscloses the circuit to ground for thetesting relays 203, v207,L etc. yover lead208, as

hereinbefore described. The .circuit Yfor' relay 317is also opened` at'the switching of the .s1-assess solootol' 40l into oosflon 13 and ,thisrelay in turn causes .the release 4of relay 303 .to remove .the,hesiter-V ,oonllootoos Vfor the. kvertical and rotarytnagnets.

The testing'osf the first ,set .of ,terminals in ylouel 2 of switches 1.and 11 Will-,now take place. This setQo terminals and the suc- ,seedingsets egt terminals in this level ,are .testeql in the same mannerasterminals in .the

,Erst level. During this testing the .selector .4,01 passing from'position 1 3 Sto ,and ,the .seleotors 406' and 411 ,pass respectivelyinto position 4. The selector 406 lights lamp 2 vin the greppel-19 ,to'iodisflto .that testing is tolsplace in the second flevol whileVseleotol 4.01 lights the urli-ts llllllps 413 .from 1 1to0 in suooossonas .the V.test -ploosefls- The ftest 4,Will 1110.11 -Proosod from sonslevel l0 another asoutlineclabove .excentthat ,when ,the switchesadvance .to the third level .the .selector 4.0.1 yWill ladrones V,itsloroshes trom .sosi- ,tion 2 2 .into position 1 ,in ,thesaine manner ,as.it is .oclroooesl into' position 13:, ood solos-tol .406 is adire-need'into position 5. The selector 401 Will then oiitornatically .adyance,the llfuslios 'finto position 3- .A .circuit .will .be completed formagnet 400 ,as follows:

Battery et the aflossen@ .and back Contact of` relay '202, Winding andselfinterrupting .oolltacts oflllg'lsill00outs .right yhanda rr1o eteresnol ibook solltest of solei 3111, brush of bank 422, .position 5toground' at ,the brush of bank 41;?, position 'From this :position theselector 4011is arluancerl into posit-M112 Where ,this Clrosit is.oss-io ,oo nipleted Vfor magnet 40.0 and the switch is therebyaglrancel.to positios ,3 Whore .the tests in the this@ lsysl wie begin. llt willtherefore los. sooo' that the selector .49.1 .will sel-stones .frompositions .3 to l2 for the rst level., 1 3 `to 22 for the sscozosllevel7 position l .to .3 ontomatloolly 'enel then proceed with thetesting ,of thethircl level odrsllooa from positions ,3' to l2. thefourth level-of ioostol.n4 .1.3 to 22. Whoa -tlos isstogfs the teo-.thlevel is .come plotegl no eirruit'isv furnished O.1`.the Verlioslloesssts .through relay .3;.19 so@ sense silently, )the siro-sits ,shovementioned, stoort" los with the operation of relsyll, ons notoororlstsd- The soleotor .4.0.1 .therefore .11e-

oial position lwitll-tho .selectors .4.06 and lll their taoltllposltioo. Under those Conditions .relay '3.0.6' .operated over .a.circuit estolloulsr battery; resisto-ooo' 324, Winding o; rslsr 30.6,loouslnof honk position .1:23 los slo 'of zbonli 402, position lfo'f,selector 40,1 to ground. This rolas/"is looked throiigh its own innerlet-t hand far-pianure Iand front con.- to .ground oyerthe brush V`ofbaril; 4 2 3, .position 1.2- 'llis operation .ofthis relay pro.- ricles.s ,battery @Connection .for tlls release magnets the' outer .leftlloolsrmatare and l`11l3-29lllzlotrlfl throngh the Winding ,otreley1322-5 Tlle-switol1ss 1,5 ll .ood 2.1 thorslorlieleassellooormslrosllioa With relay 306 .operated a connection is established formagnet 408 from battery through the .Winding and self-interruptingcontacts of .this magnet through .the :third outer right hand armature,and Vfront ,con- .tact of vrelay 30,6 .to ,the brush .ofhank 425,position 12, brush of hanl`426, posities 2 ,et

selector 42,7' .t0 ground at the third touter left' .right hand.armature and .tron-.toontact ot re- ,306, brush of 431, positions 22and1, brush of bank 425,13ostien 2, hrushof bank 426, position 2, .third,outer left hand armature and iront tcori-act of relay 30,6 4toj.groungl. A vcircuit is `completed for magnet .4149i selector 411 asfollows. Batterygviridingand .self-interrupting. contacts .O111%lgnet'414,

,outer right hanel Yarmature .and .front Io ontaot s ition 12, fbrush ofbank .431, posgl-tif'gn 2 'of selector 401, brush .of barili 425,position2 ojl selector .40.5, brush t of hanl.4 2 6,position2 ,ofselector .42,7 .to ground at the .third outer left hand armature andfront ,Contact 1of revlay 4306. ySince terminal and terminals ,3 @122isole-siro strorrofl together osos ynet 4 l4eontinues to opera-te andrelease ,until .this switch s rst-uros@ to normal., position' When allofthe seleotors have returneelto .normal 1the ,orout iorrelay isshun-,ted through the brash of harikf430 at position .2 to th groundflroisheol tlolousll hooks A43.1, 425 and 426 and when relay/,306released .a circuit is ,completed for the lighting of lamp .326 frenigroundfthrough thelarnp, thegthirel .outer lar rrlagture hackoontaotfofrelay 3016 .banks 4.2.6, 42,5, 4.31 sod 430 toloottery lhrfoogloresistono@ .324- Ths lighting ,oit this .lamp

dieates that the Switches are in norrnal .po-

sition and Athat ,the -testingo the v. switches 1,11a1id21hasbeencompletsd.. f l

To test Switchs 2, l2 olol 2.2 the :transfer lfrey 200 is operated. Theleads extending to Vswitches 1, 11 and 21 are .thereby opened'corresponding leads connected to the brushes, trames ,and ,operatingmagnetsY of switches 2, 12 and .2.2. The tsstog fof .these switchesv moynow proceed in the -saineman-ner vlas thetest lso lng-of the proosdiosswitches and the testing .is .started A.operetti-1g the start key'OO.

While these switches are being tested 'the lost 111.213/ `rdi.sooollootthe loads ,from iswtohss 1,11 and Qliand ysoonest them to switches 3,I1,3 and 2 3 .respeotivelyanl when the testing Q f switches 2, 12 and 22is com- Plotodftllo .swllhssfl and 23 :moy loe Atesto by returning thetransfer key 200 toA normal and while these switches are being testedthe leads for switches 2, 12 and 22 are disconnected by the test man andconnected to the switches 4,14 and 24, etc. until the whole group ofthirty switches have been tested. In this manner the testing of a groupof thirty switches maybe completed by originally con'- nectingl twogroups of three switches each to the transfer keys and changing theconnections from one 'group of three switches at a Y time'eightsuccessive times.

' v andl 216 are not operated to switch the testing frombetween thefirst and secondswitches to testing betweenV the second and a thirdswitch asno third switch is connectedfor testing. u In this case theoperating circuits for lthese relays are opened by the operation ofkkey201 and consequently relays 312 lor v313 will not operate and neitherwill lamps 2 3 be lighted.V Relay V3,14 instead of operating throughcontacts yof relay 313 will be oplerated through contacts of key 201 toswitch the selectors from one position to another to ences in thecircuit arrangement which will Y be hereinafter pointed out.

control the tests of succeeding sets of terminals. It should also benoted that withkey 325 operated as described above, the circuit forpartially operating the vertical magnets includes resistance 320; thisadditional resistance is required since in this case konly two verticalmagnets are operated in parallel instead of three being operated inparallel'asf is thecase when testing a group of thirty switches. Itisbelieved that no further description is necessary in regard to thetestingof agroup ofy twenty switches, in view yofthe'-above'remarksandthe previous complete description of the procedure inV testing [la z'groupfof `thirty switches.

, In'testinga group of 16 switches the procedure is thesame Vas intesting a group of 20 switches assfar as the testing of switches :1 to 6and 11 .to 1K6 is concerned. When the testing y has been" completed tothis point switches 7 `and l9 and Sand 10 are't'ested in a similarmanner but jwith a few minoridier-v At' this time keys 305 and V20,1 areoperated and "key/7325* is in normalposition.` VThe switches 7 and 8 arein this case connected as switches 11 and 12res`pectively shown in Fig.1, while switchesv 9 `and 10 are Vconnected as switche'sl'and2`respect'ively shown in Fig; 1.

. Y .The first effect'fromthe "operation of key 305l isfthatkthevertical magnet of'switch 7 or switch 8, depending on the operation ofthe transfer key 200, will now receive an ac` tuating impulse throughthe operated lefthand contacts of key`305.' The circuit may betraced,'for example, fromthe vertical magnet of switch 7, through lead43,r transfer key 200, key 305, brush of bank 433, position 2,

brush of bank V402, position 3 to ground. Itl

should be noted that the selector 401 'will have its brushesV inposition-3 at this time having been operated and' returnedto thisposition thirty successive times during ythe testing of the other 12switches. Selector 427 lwill now step from position 2 into position 3atthe same time as selector 406is stepped from Y position 2 into position3V over a circuit as hereinbefore traced. Thecircuit for magnet 434ofselector 427 may be traced from batp I tery through the magnet 434 andits self Y interrupting contacts, left-hand armature and front contactof relay 304, brush of bank 436,

posit-ion 2, right-'hand closed contactsofkey y305, to ground at theinner left-hand armature and Contact of relayv 306. YIn the case of thevertical magnet of switch 9 or V10, thefirst actuating impulse .will berreceived through a circuit closed in the same mannerasfbefore, that is,through brush of bank 407, position 2 and bank 402, positiony 3 tovground.

With selector 427 in position 3, relay 303 is operated over a circuit.from .ground through brush of bank '409 to continue to feed battery tothe vertical magnets. It should ybe noted that lthis vrelay is alsooperated for the .A

same purpose as the selector passes from position 3 through positions 4,5 and 6. Selector 427 in position'3 also closes an operating circuit forits stepping magnet 434to step it into the fourth posit-ion. Thiscircuit may be traced as follows: jbattery, winding andthe'self-interrupting contacts of magnet 434, brush of bank436,`position 3, key 305 to ground at relay 306. Withselector 427k inposition 4 a circuit is closed-for transmitting j i a second impulse-for the vertical magnetpof switch' 7 or 8. This circuit will be `closedthroughkey 305, brush of .bank 433, position 4, vbrush of bank 402,position 3jto ground.

Atthe same time a circuitis'closed .for the operationof relay 326frombattery, through the winding ofthis relay, brush of bank 435,

position 4, key 305 to1 groundsat relay l306. This relay, however, isslow to operate so that ample time 'is allowedv for the operation of thevertical magnet of switch 7 for.8v the second time over the abovecircuit. Relay v326 in operating closes a' circuit for selector 427to-advance it Vto the fifth position' The'cir-` cuit in this case willbe frombatterythrough the .winding and self-interrupting contactsof'relay 434, armature and front contactV of relay Y 326, brushofbank435 position 4, key 305'to ground 'at relay 306. In this position relay326 isA released and selectorl427 closes a circuit kformoving it intothe sixth position as follows: from battery, through the winding 4andself-interrupting contacts `vof magnetv 434, brush of bank 436, position5, key 305 and ground at relay 306. lIn position V6 a ci-rcuit is closedfor the third time -orthe vertical `magnet of switch 7 'or V8 'over thebrush of "bank 433, .position 6, fand fthe above Imentioned circuit kiorrelay 326 is again closed through the brush of bank 435. -Relay 326 4inopera-ting rcloses a'=circuit for vmagnet 434 through -brushof bank435,k position '6, to ad vance the switch v427 into its seventhposition. Relay :326 is now again released.

In position7 xa circuit is closed for the lrotary magnet oit switch` -7Ior 8 and yalso for switch 9 or 10. This circuit'may be traced asfollows: at thetransfer key 200 trom lead 35 or 8 for rotarymagnetofiswitch'tl or 10 and from lead 34 "0r 17 for rotary magnetof'switch fr' or 8, through brush of bank 412, position 2, 'brush ofbank 413, position r3, brush of bank 435, position '7, key 305 to groundat relay v306. Relay "308 will be operated `at the same time, over a'circuit from battery, winding of relay A308, rush oi 'bank 409,position '3, brush ofbank 410,position 2, brush oi' bank 435, position7, key 305 to ground at relay 306. This relayin-operating closes acircuit `for the stepping of selector 1 411 into .position3 'as follows:battery, winding` and self-interrupting contacts of magnet 414, armatureand trontcontact ofrelay 308, brush of bank 410, position 2, brush ofbank 435, position 7, key 305 to rground at relay 306. The testing fromthis Ipointon will proceed as tor a 20 switch unit until the eighthlevels of the switches have been tested.y

It vshould be pointed out-at vth'is time that the vertical magnet ofswitch 7 or 8 has 'now been operated three times while the verticalmagnet for switch 9 kor 10 has operated once. The vertical and rotarymagnets of switches 7 or 8 and of switches 9 or 10, willirom this pointon operate in the same manner as the 20 switch units test. The testingwill therefore start `in the cases of switches 7 4and 8 on the thirdlevel and in the cases 'of switches 9 and 10 on the first level. Thetesting will now proceed until the eighth level of switch 9 or 10 anduntil the tenth level of switch 7 or 8 is tested. From this pointltheftesting will proceed as follows: The first level of switch 7 or 8 willbe tested with'the level9 of switch 9 or 10 and the second level ofswitch 7 or 8 will be'tested with the level 10 :of switch 9 or 10. rlhecircuit in which the lvertical magnet of switch 7 or 8-is partiallydperated, after the test of the tenth set of contacts in levels 3 to 9inclusive, istra'ced 'fromiits'winding over lead 43 or lead 16, throughkey200, lett-hand normally open contacts of key-305, terminal 7 andbrush of 'bank 438, brush of bank 439 yin any of positions '3 to 9inclusive, winding of relay 319, resistance-320, lany one of terminals 3to 9 inclusive, and'brush of bank 422, lterminal 12 or 22 and vbrush rofbank A416, back lContact of relay v314, front contact oi relay 309,brush of Vbank 415;, Vback contact of relay 3'10,=andbackcontactoitrelay311, to ground. The circuit in which the vertical magnetxor switch 9'or.10 is partially operated, Aafter 'the 7test toil? Lthe tenth set ofcontacts in llevels 1 ito 8, is Itraced :iromits Winding over lead 34 orlead 7, through key 200, to'the winding of relay `319, and 'thereiafterthe saine as the circuit fr 'the vertical magnet :of switch 7 or 8. Thepurpose :of arranging the testing in this manner `for ythe lastftourswitches fin La 16'switch unit is that the multiple lconnections betweenthe stvitchesare-slipped so that for example, the m'nltiple connectionsfrom the lterminals in the third #level of switches 7 `and l8 willbeieX- tended Pto -the terminals iin the yfirst flevel oswitches `9 and10. This stepping arrangement is 'ofrno particular importance 'of itselfbut simply serves as a means 'of illustrating how the'inventionmaybeapplied to thetestingof 'switches having slipped 'fmultiple connections.Y

When *the Vrelease magnets Loi l switches 7701` Sand `9 `or 102a're'operated,-lafter testing the connections Ibetween the ten-thlevel ofswitch 7'lor 8 fand the eighth level oi switch 9or .10,

it is necessary toinsertan additional ,resistance 437 in series with therelay 319 and resistance 320 in the circuit of 'the vetilcalma'gnet 'ofswitch 9 or f'10so as .tooniy partially energize this verticalfmagnetand ftliius permit the restoration oi' the brushes of switch`=90r 10 in-a rotary idirection only., 'while the brushes o'f switch 7 for 8 areYbei 'restored in l'both the rotary 'and ithe vertical directions. Itresistance A'3200nly was tinserted Ainthe .tircuit for the `vertical.magnet fof fswitch .9 l,or 10 fit might 'be 'energized'tofsuchfanfenten-t :as to have the lpaw-l 4thereof dragfor llbin'd 'on:a vertical tooth and vhence interfere with :the rotary "release-Forthis reason fthe-arrange ment is -such that the ladditional;:resistance 437 is included Xinthe circuit forthe vertical magnetlofswitcha9 or 10 'whilefoircuit for the vertical:magnetfofswitch 7 'or8fisope'ned 5to permit the corresponding switch to return to normal and'this circuit is lateragainclosed tocause the :corresponding magnet to.operate fully to continue the test in level's flfand2.

This additional resistance is inserted Y as noted while -thevsele'c'torf411 is in -its Vtenth position as k'eyV y1325'is released. It Iwill beobserved that rthe y'circuit 'of vertical magnet forl switc'h'f9o'r .'10will kat thiswtime zbe rtraced as follows 'from eitherotjthesemagnetsover lead34ior 7 through key 200, lwindingeffi-1elay 319,res-istance 320, resistance 437-,ybrus'h oi bank 422, position 10, brush'otfba'nkf416, position 'f22,rback Contact of relay 314, front contact.of rela-y :309, brush of f-bank 415, position 22, back contacts-otrelays31Oand .311 to ground. Nozcircuitfis'comp-leted a't this time forthe verticalmagnets of switch 7 or.' 8 as the normal circuit through key305 is opened' at the brushof bank 436 due to the fact that selector 427is in its seventh posi Switch 7 or 8 will therefore now release in theusual manner yfrom the tenth level while switches 9 and 10 will continueto be tested through theninth and tenth levels. When the switch 7 or 8has released .its vertical magnet it will again receive full potentialdue to the operation of relay 323 in the usual manner. rl`he` circuit inthis case will be as follows: vertical magnet of switch 7 or 8,

, lead 43 or 16, transfer key 200, key 305, brush of banky 438, position7, brush. of bank 439, position 10, yright-hand larmature ,and frontcontact ofrelay 323, ground at the armature andffront contact of relayV316. Relay 316 is operated in the usualv manner to cause the fulloperation at this time also of the vertical magnet of'switch 9 or 10 sothat the testing willproceed as usual through the ninth and tenth levelsof these switches in unison with the first and second levels of switches`7 or 8.

I 1 ing, throughl resistance 324 and through these selectors when inposition 2 will not be coinpletedat this time through the brush of bank426 as this selector is not yet returned to normal. A circuit willhowever now be completed for the return of selector 427 as follows:battery, winding and selfinterrupting contacts of magnet 434, secondouter left lcontact of relay 306, through thev succeeding contacts ofthe remaining'positionsof selector 427 andto the brush of bank 426,third outer Aleft-hand contact Vand armature of relay1306 to ground.When selector 427 has returned -to normal relay 306 is short circuitedandreleases and consequently the circuits of the system are restored tonormal as hereinbefore described in connection with 20 and 30 switchunits. A 'Y f It should be understood that, while the invention has onlybeen illustratedin connection with testing of switches, it is notconfined to these arrangements but may readily bel applied in othersystems without departing from the spirit thereof, and that theinventionshould only be limited'by the scope of the appended claims.

What is claimed is:

l. A plurality of switches, wipers therefor, means for moving the wipersof two switches in, synchronism in a primary movement in one directionfollowed'bya secondary move-- When the selectors 401,.

ment in another direction, meansfor releas- 'l ing-said switches inregardto the-secondary movement, and means for continuing the primarymovement a'nd yrepeating said movements .in the .order mentioned.;

2. A plurality of switches, wipers therefor, n

term-inalsin said Vswitches arrangedinlevels, means for moving theYwipers oftwo switches in synchronism over the terminals ofsucceed-A inglevels, means for releasing-said switches,

and means operative after said release` for moving the wipers of oneofsaid switches and another switch in synchronismoverthe terminals ofthe succeeding levels.

3. A pluralityof switches having two-div rection wipers, individualmeans for controlling the wipers of two switches simultaneous-f.

ly to execute avertical movement followed.

by a rotary movement, means fork releasing said wipers as regardsbothmovements, and

means -forpreventing said release as regards.,

the vertical movement. I

4. A switch Vvhaving two-direction wipers, a first magnet forcontrolling thek wipers in a iirst movement, a second magnet forcontrolling the wipers in asecond movement,

ymeans zfor releasing said Ywipers as regards both movements and meansfor controllingV the first magnet to prevent the release as regards thefirst'movement from becoming effective.` y c v5.. Switches havingtheir-wipers movable in two directions.V and their corresponding sets ofterminals multipled,.in combination with va testing devicecomprisingmeans for moving the wipers of two of said switches at e a time tosimultaneously engage theirfcorresponding'setsof terminals forthetesting of the multiple connections therebetween, andr f meanscontrolling the movement of said wipers in the two directions to preventthe releasev to normalv while changing totheother. 1 c.

6. Switches having their wipers movable in' two directions and theircorresponding sets of terminals arranged in layers and mul'- tipledtogether, in combination with atesting device comprising meansforcontrolling the fromone direction movement of wipers'of two switches tocauseV saidwip'ers to simultaneously engage 'their corresponding sets ofterminals in the succeeding layers, and means toprevent the wipers fromreturning to normal while shifting from one layer to another. Y

7. A'plurality of multi-level switches, sets of wipers in each switch,sets of terminals in each level of said switches accessible from thecorresponding sets `of wipers, means for causingthe sets of wipers oftwo switches to move in synchronism in one level over the sets ofterminals therein, means effective when saidsets of wipers reach theirlimit of motion for restoring Vthewipers to their position op'-vpositeisaid levels and for movingsaid wipers to the correspondingsucceedingA levels, saidVv movement automatically continuing from levelto level over the corresponding sets oit' terminals in succession.

8. A plurality of switches comprising sets of terminals divided ingroups, a corresponding set of wipers for each switch, a primary magnetfor each switch, a secondary magnet for each switch, means foro-perating said primary magnets to direct the corresponding wipers fromgroup to gro-up, and means for operating said secondary magnets fordirecting the corresponding wipers over the sets of terminals in saidgroups, and means for co-ntrolling the movements of said magnets of twoswitches to operate in synchronism and to automatically continue theactuation of the wipers to travel over the sets of terminals insucceeding groups.

9. A plurality of switches having multiple connections between theirterminals, a testing device, means for connecting three switches to saidtesting device, and means l for causing said device to test theconnections between the first and the second of said connected switchesand thereafter the connection between the second and the third of saidconnected switches.

10. A plurality of switches having multiple connections between theirterminals, means for testing Jfor unstandard conditions in the multipleconnection between any pair of switches, means for connecting a firstand a second pair of switches to said testing means simultaneously, andmeans for switching the testing means from the rst pair of switches whentested to the second pair for testing.

1l. A plurality of switches having multiple connections between theirtermina-ls, means for testing for unstandard conditions in the multipleconnection between any pair of switches, means for connecting a firstand a second pair of switches to said testing means simultaneously,means for switching the testing means from the irst pair of switcheswhen tested to the second pair for testing, and means for connecting athird pair of switches to said testing means while the second pair isbeing tested.

l2. A plurality or" switches, wipers therefor, terminals in saidswitches arranged in levels, multiple connections for the correspondingterminals of succeeding switches, means for moving the wipers of two ofsaid switches in synchronism over the corresponding terminals ofsucceeding levels, and means for indicating unstandard conditions in themultiple connection when the wipers make contact with correspondingterminals of the two switches.

13. A plurality of switches having terminals arranged in levels,multiple connections between the corresponding terminals of saidswitches, means for testing for unstandard conditions in said multipleconnections between any pair of switches, means for indicating anyunstandard conditions encountered during testing, and means forindicating the progress of a test comprising signals

